Definition of an Identity Matrix

Date: 08/09/99 at 12:00:59
From: noor
Subject: Identity Matrix
Can someone please tell me what is the definition of an identity
matrix? Which of the following would be an identity matrix?
-1 2 1 -3 -2 2
3 -4 -5 7 3 -4
-5 6

Date: 08/10/99 at 01:28:11
From: Doctor Rob
Subject: Re: Identity Matrix
None of these is an identity matrix. An identity matrix must be a
square. All the off-diagonal entries are zero. Finally, the entries on
the main diagonal are all ones. For example,
[1 0 0]
[0 1 0]
[0 0 1]
- Doctor Rob, The Math Forum
http://mathforum.org/dr.math/